Hair Loss Breakthrough: Grow Hair via Plucking

Researchers at the University of Southern California have shown that the regrowth of lost hairs can be stimulated by the ordered, patterned plucking of remaining hairs in mouse models. It is hoped that these findings may lead to the development of a much-needed treatment for hair loss in humans.

Hair Loss – The Basics

To the general public, alopecia represents a partial or complete lack of hair growth. Most often associated with men as they get older (‘male pattern baldness’), overall hair loss is now proven to have negative psychological implications. To this day, surgical grafting remains the most drastic measure taken to compensate for the loss of hair. However, it is expensive, painful and its success is highly dependent of the chosen surgeon and methods such as follicular unit extraction (FUE).

A New Approach

In the fight against hair loss, the plucking of hairs in a deliberate, coordinated manner has been proven to result in a 5-fold increases in localized hair growth, according to a recent study published by USC researcher Dr Cheng Ming Chuong.

The study, conducted in mice, showed that plucking individual hair follicles triggers a cascade of signalling events which ultimately stimulates hair growth in the area. (1)

Researchers explained that by damaging follicles, hair plucking stimulates the release of an inflammatory protein termed CCL2. Once released, CCL2 recruits specific immune cells to the area. These immune cells, termed macrophages, then release a cell-signalling molecule, termed TNFα, which stimulates the regeneration of all nearby hair follicles, resulting in a 5-fold increase in hair growth.

A Hair Follicle Can Only Regenerate in Concert with Other Follicles, but Not by Itself

(A) When the density of plucked hairs from the mouse skin is lower than a certain density (i.e., “threshold density”), no follicles regenerate. If the density of plucked hairs is higher than the threshold, all the follicles of plucked hairs (“distressed follicles”) and the follicles of surrounding intact hairs (“healthy follicles”) regenerate by entering growth (anagen) phase from a dormant (telogen) phase.

(D) Main factors that a group of cells may use to collectively make a binary decision.

A Hair Follicle Can Only Regenerate in Concert with Other Follicles, but Not by Itself

(A) When the density of plucked hairs from the mouse skin is lower than a certain density (i.e., “threshold density”), no follicles regenerate. If the density of plucked hairs is higher than the threshold, all the follicles of plucked hairs (“distressed follicles”) and the follicles of surrounding intact hairs (“healthy follicles”) regenerate by entering growth (anagen) phase from a dormant (telogen) phase.

(D) Main factors that a group of cells may use to collectively make a binary decision.

A Hair Follicle Can Only Regenerate in Concert with Other Follicles, but Not by Itself

(A) When the density of plucked hairs from the mouse skin is lower than a certain density (i.e., “threshold density”), no follicles regenerate. If the density of plucked hairs is higher than the threshold, all the follicles of plucked hairs (“distressed follicles”) and the follicles of surrounding intact hairs (“healthy follicles”) regenerate by entering growth (anagen) phase from a dormant (telogen) phase.

(D) Main factors that a group of cells may use to collectively make a binary decision.

A Hair Follicle Can Only Regenerate in Concert with Other Follicles, but Not by Itself

(A) When the density of plucked hairs from the mouse skin is lower than a certain density (i.e., “threshold density”), no follicles regenerate. If the density of plucked hairs is higher than the threshold, all the follicles of plucked hairs (“distressed follicles”) and the follicles of surrounding intact hairs (“healthy follicles”) regenerate by entering growth (anagen) phase from a dormant (telogen) phase.

(D) Main factors that a group of cells may use to collectively make a binary decision.

Chuong claims that this ability of hair follicles to produce a concerted response to hair plucking is an example of a process termed quorum sensing.

Quorum sensing is the means by which certain cell populations are able to make coordinated, group decisions in response to stress or damage; by successfully communicating information between cells, typically via cell-signalling molecules, a collection of cells can produce an appropriate, population-level response to certain types of damage.

Chuong describes the process as a type of collective cellular behaviour in which each follicle “becomes a sensor for the population,” allowing the population to “assess the level of damage” caused by a stimuli and subsequently make a collective, responsive decision. (1)

Molecular Basis of Quorum-Sensing Behavior during the Activation of Hair Stem Cells in the Follicle Population Schematic illustration of the process.
A visual representation of the series of events linking hair plucking to activation of hair follicles and the resultant increase in localised hair growth. Telogen follicles are resting, non-stimulated hair follicles, whilst anagen follicles are active, stimulated hair follicles. (1) (Credit: “Enhance hair growth via plucking” [D2014-0054], University of Southern California).

Stage i: minor injury/hair keratinocyte apoptosis/CCL2 production.

Stage ii: CCL2 secretion / macrophage accumulation.

Stage iii: macrophage and Tnf-a permeate the whole region.

Stage iv: Tnf-a activates hair regeneration in the whole region.

Hair regeneration further spreads due to propagation of regenerative hair waves.

Molecular Basis of Quorum-Sensing Behavior during the Activation of Hair Stem Cells in the Follicle Population Schematic illustration of the process.

Hair regeneration further spreads due to propagation of regenerative hair waves.

Whilst the study was conducted in mouse models, Chuong is hopeful the findings will translate to humans, and may therefore eventually lead to a new treatment for hair loss. The real-world impact of such a treatment would be enormous, as globally over 50% of adults, both men and women, suffer from hair loss at some point in their lives. (2)

“It is a good example of how basic research can lead to work with potential translational value,” claimed Dr Chuong, who believes that the study has provided “potential new targets for treating alopecia.” (3)

One specific type of alopecia, termed male pattern baldness (MPB), is currently the predominant cause of hair loss amongst U.S. men, affecting over 66% of American men aged 35 and above.

Hair loss affects a huge number of U.S. individuals, both men and women. Many of these individuals turn to the most effective and dramatic treatment for hair loss currently available, surgical follicle grafts. (7)

Hair loss affects a huge number of U.S. individuals, both men and women. Many of these individuals turn to the most effective and dramatic treatment for hair loss currently available, surgical follicle grafts. (7)

Hair loss affects a huge number of U.S. individuals, both men and women. Many of these individuals turn to the most effective and dramatic treatment for hair loss currently available, surgical follicle grafts. (7)

Hair loss affects a huge number of U.S. individuals, both men and women. Many of these individuals turn to the most effective and dramatic treatment for hair loss currently available, surgical follicle grafts. (7)

Whilst MPB it is not itself a painful or dangerous condition, it can cause sufferers a significant amount of psychological stress; feelings of depression, helplessness, and general feelings of worry have all been associated with the condition. (4)(5)(6)

There is currently no cure for male pattern baldness, and whilst some treatments (such as minoxidil and finasteride) can slow the progression of hair loss in some men, many find that a surgical graft of hair follicles is the only way to effectively maintain, or regain, a full head of hair. (7)

Due to the risks, cost and stress inherent to any surgical procedure, surgical grafting is far from ideal as a treatment. It is therefore hoped that research into ordered hair plucking will provide a far less invasive, costly and intensive therapeutic alternative.

Plucking-Induced Hair Regeneration Is a Population-Based Behavior that Depends on the Density and Distribution of Plucked-Hair Follicles within the Unplucked Follicle Population

(C) Plucking induces regeneration of all follicles (the 200 plucked and 600 unplucked) within the plucked area (red circle, 5 mm in diameter). Unplucked follicles (400 HFs in total) outside the plucked area boundary then regenerate due to hair wave propagation (blue circle).

(D) High power view showing unplucked follicle regeneration: the old gray club hair (yellow) is pushed out by the regenerating black anagen hair (red).

(F) Plot showing the hair regeneration response versus the size of the plucked field. For all different field sizes, 200 hairs are plucked evenly dispersed throughout the field. A regenerative response is observed when 200 hairs are plucked at a density above a threshold (10 hairs/mm2), which corresponds to plucking 200 hairs from a 5-mm diameter circular surface area (red line). Three responses represented by different colors (gray, tan, green), are observed (please see text for explanation). The quorum sensing zone is highlighted in orange.

(C) Plucking induces regeneration of all follicles (the 200 plucked and 600 unplucked) within the plucked area (red circle, 5 mm in diameter). Unplucked follicles (400 HFs in total) outside the plucked area boundary then regenerate due to hair wave propagation (blue circle).

(D) High power view showing unplucked follicle regeneration: the old gray club hair (yellow) is pushed out by the regenerating black anagen hair (red).

(F) Plot showing the hair regeneration response versus the size of the plucked field. For all different field sizes, 200 hairs are plucked evenly dispersed throughout the field. A regenerative response is observed when 200 hairs are plucked at a density above a threshold (10 hairs/mm2), which corresponds to plucking 200 hairs from a 5-mm diameter circular surface area (red line). Three responses represented by different colors (gray, tan, green), are observed (please see text for explanation). The quorum sensing zone is highlighted in orange.

(C) Plucking induces regeneration of all follicles (the 200 plucked and 600 unplucked) within the plucked area (red circle, 5 mm in diameter). Unplucked follicles (400 HFs in total) outside the plucked area boundary then regenerate due to hair wave propagation (blue circle).

(D) High power view showing unplucked follicle regeneration: the old gray club hair (yellow) is pushed out by the regenerating black anagen hair (red).

(F) Plot showing the hair regeneration response versus the size of the plucked field. For all different field sizes, 200 hairs are plucked evenly dispersed throughout the field. A regenerative response is observed when 200 hairs are plucked at a density above a threshold (10 hairs/mm2), which corresponds to plucking 200 hairs from a 5-mm diameter circular surface area (red line). Three responses represented by different colors (gray, tan, green), are observed (please see text for explanation). The quorum sensing zone is highlighted in orange.

(C) Plucking induces regeneration of all follicles (the 200 plucked and 600 unplucked) within the plucked area (red circle, 5 mm in diameter). Unplucked follicles (400 HFs in total) outside the plucked area boundary then regenerate due to hair wave propagation (blue circle).

(D) High power view showing unplucked follicle regeneration: the old gray club hair (yellow) is pushed out by the regenerating black anagen hair (red).

(F) Plot showing the hair regeneration response versus the size of the plucked field. For all different field sizes, 200 hairs are plucked evenly dispersed throughout the field. A regenerative response is observed when 200 hairs are plucked at a density above a threshold (10 hairs/mm2), which corresponds to plucking 200 hairs from a 5-mm diameter circular surface area (red line). Three responses represented by different colors (gray, tan, green), are observed (please see text for explanation). The quorum sensing zone is highlighted in orange.

Christopher Edward Jones is a biochemist and writer currently affiliated with Queen Mary University of London, where he is part of a research group focusing on the restriction factors of HIV. In the past he has worked with multiple biomedical research groups in both industry and academia. He has a research interest in the biochemical mechanisms of virus restriction and a general interest in all areas of science.

Christopher Edward Jones is a biochemist and writer currently affiliated with Queen Mary University of London, where he is part of a research group focusing on the restriction factors of HIV. In the past he has worked with multiple biomedical research groups in both industry and academia. He has a research interest in the biochemical mechanisms of virus restriction and a general interest in all areas of science.

Christopher Edward Jones is a biochemist and writer currently affiliated with Queen Mary University of London, where he is part of a research group focusing on the restriction factors of HIV. In the past he has worked with multiple biomedical research groups in both industry and academia. He has a research interest in the biochemical mechanisms of virus restriction and a general interest in all areas of science.

Christopher Edward Jones is a biochemist and writer currently affiliated with Queen Mary University of London, where he is part of a research group focusing on the restriction factors of HIV. In the past he has worked with multiple biomedical research groups in both industry and academia. He has a research interest in the biochemical mechanisms of virus restriction and a general interest in all areas of science.